The present invention relates to lasers and, more particularly, to a laser power meter for measuring the power in a laser beam or the like.
Presently, the only practical way of determining the output power of a laser is by empirically measuring the power in its beam. To this end, power meters have been designed for intercepting the output beam of a laser and providing a reading representative of its power. In general, such power meters include a solid state photocell, generally a silicone solar cell, which generates an electrical output potential in response to the interception of a laser beam. The potential is then fed to an indicator, such as the needle of a meter, which will register the power as a function proportional to the value of such electrical potential.
The difficulty with power meters presently available for such purpose is that the response of the sensors used in them is dependent on the wavelength (typically measured in nanometers) of the intercepted beam, as well as on its power. The result is that changes in the electrical output potential of such sensor are not proportional to power changes, and power meters consequently can provide a true reading of power only at a specified wavelength rather than over the full range of wavelengths which might be encountered in different output beams of, for example, dye or ion lasers. Because photocells which are not wavelength dependent are not yet available, makers of laser power meters have provided users with correction curves or multiplication factors which enable the users to extrapolate to other wavelengths, a power reading for a wavelength for which the power meter is designed. The necessity of using correction curves or multiplication factors makes it inconvenient to use a power meter to measure the power of any laser beam having a significantly different wavelength than that for which the power meter is designed.